1. Field
The following description relates to a particulate matter reduction apparatus for a diesel engine, which reduces particulate matters in exhaust gas discharged from a diesel engine.
2. Description of the Related Art
A diesel engine employed in an automobile, a diesel vessel and a diesel locomotive has is advantages of superior fuel economy and powerful output, however it is by its nature bound to discharge a significant amount of particulate matters included in the exhaust gas, unlike a gasoline engine.
Since particulate matters are regarded as a main factor of air pollution, regulations limiting the particulate matters have been tightened. Accordingly, a diesel engine is equipped with a diesel particulate filter (DPF) to reduce the discharge amount of particulate matter. The DPF acts to collect particulate matter exhausted from the diesel engine to reduce it.
In use of the DPF, a method of removing the collected particulate matter has arisen as a key issue. For example, a method of separating a filter and washing it has been introduced. However, although this method does not require a diesel vehicle to be equipped with another device, it does cause users the inconvenience of having to exchange filters periodically.
As another example, a method of burning particulate matter collected in a filter has been suggested. According to the method, an electric heater or a diesel burner is installed in a portion of the filter in which exhaust gas flows, and the exhaust gas is heated to a temperature that is capable of igniting particulate matter inside the exhaust gas.
However, since the above method requires an electric heater or a diesel burner to be additionally installed, it complicates the structure of the filter and increases manufacturing cost. Moreover, a portion of the filter close to the electric heater or the diesel burner can be overheated, and consequently it may shorten the lifespan of the filter.
As another example, a method of adding an additive to fuels to promote combustion of particulate matter collected on a filter at a low temperature, and a method of applying a catalyst to the filter have been introduced. However, the use of an additive is disadvantageous in that a specific type of a fuel must be used, for example, mass fraction of sulfur contained in the fuel is should be smaller than a certain value. Furthermore, the method of applying a catalyst to a filter is not as efficient as the method of adding the additive in fuels in terms of lowering a temperature that is capable of igniting particulate matter, and thus an additional heat source or additive is required.